The growth of wind energy penetration level in distribution system raises the concern about its impact on the operation of the power system, especially voltage stability and power loss. Among the major concerns, this ...The growth of wind energy penetration level in distribution system raises the concern about its impact on the operation of the power system, especially voltage stability and power loss. Among the major concerns, this paper studied the impact of connecting wind Turbine (WT) in radial distribution system with different penetration levels and different power factor (lead and lag) on power system voltage stability and power loss reduction. Load flow calculation was carried out using forward-backward sweep method. The analysis proceeds on 9- and 33-bus radial distribution systems. Results show that voltage stability enhancement and power loss reduction should be considered as WT installation objective.展开更多
目的探讨骨骼肌质量指数(Skeletal muscle mass index,SMI)、肌少症指数(Sarcope-nia index,SI)与呼吸危重症患者营养状态及预后的关系。方法选取2021年9月至2023年8月南通市第一人民医院收治的呼吸危重患者132例。采用改良危重症营养...目的探讨骨骼肌质量指数(Skeletal muscle mass index,SMI)、肌少症指数(Sarcope-nia index,SI)与呼吸危重症患者营养状态及预后的关系。方法选取2021年9月至2023年8月南通市第一人民医院收治的呼吸危重患者132例。采用改良危重症营养风险评分表(The modi-fied nutrition risk in critically ill,mNUTRIC)评估患者营养状况,根据评分结果分为低风险患者(n=83)、高风险患者(n=49),比较低风险患者与高风险患者的SMI、SI。以离开ICU为时间终点评估预后,分为死亡组(n=37)和存活组(n=95),比较死亡组与存活组患者的一般资料,采用多因素Logistic回归模型分析影响呼吸危重症患者死亡的因素,受试者工作特征(Receiver operator characteristic,ROC)曲线分析SMI、SI预测呼吸危重症患者死亡的风险价值。结果与低风险患者相比,高风险患者的SMI、SI降低(P<0.05)。以离开重症监护室(Intensive care unit,ICU)为评估时间终点,与存活组相比,死亡组年龄、入院24 h内的急性生理评分、年龄评分及慢性健康评分(Acute physiology and chronic health evaluation scoring system,APACHEⅡ)评分及降钙素原(Procalcitonin,PCT)水平较高,白蛋白(Albumin,ALB)、SI和SMI则较低(P<0.05)。多因素Logistic回归模型显示,高APACHEⅡ评分及低SMI、SI值是影响呼吸危重症死亡的独立危险因素。ROC曲线显示,SMI、SI单独预测呼吸危重症患者死亡的曲线下面积(Area under curve,AUC)为0.784(0.720~0.839)、0.726(0.657~0.788),采用SMI、SI联合预测AUC为0.890(0.835~0.938),联合预测效能较单独预测效能更好(P<0.05)。结论SMI、SI与呼吸危重症患者营养状态关系密切,两者联合预测呼吸危重症患者死亡的临床价值高于单独预测。展开更多
Two common problems for a typical Power distribution system are voltage collapse & instability. Challenge is to identify the vulnerable nodes and apply the effective corrective actions. This paper presents a proba...Two common problems for a typical Power distribution system are voltage collapse & instability. Challenge is to identify the vulnerable nodes and apply the effective corrective actions. This paper presents a probabilistic fuzzy approach to assess the node status and proposes feeder reconfiguration as a method to address the same. Feeder reconfiguration is altering the topological structures of distribution feeders by changing the open/closed states of the sectionalizing and ties switches. The solution is converge using a probabilistic fuzzy modeled solution, which defines the nodal vulnerability index (VI) as a function of node voltage and node voltage stability index and predicts nodes critical to voltage collapse. The information is further used to plan best combination of feeders from each loop in distribution system to be switched out such that the resulting configuration gives the optimal performance i.e. best voltage profile and minimal kW losses. The proposed method is tested on established radial distribution system and results are presented.展开更多
文摘The growth of wind energy penetration level in distribution system raises the concern about its impact on the operation of the power system, especially voltage stability and power loss. Among the major concerns, this paper studied the impact of connecting wind Turbine (WT) in radial distribution system with different penetration levels and different power factor (lead and lag) on power system voltage stability and power loss reduction. Load flow calculation was carried out using forward-backward sweep method. The analysis proceeds on 9- and 33-bus radial distribution systems. Results show that voltage stability enhancement and power loss reduction should be considered as WT installation objective.
文摘目的探讨骨骼肌质量指数(Skeletal muscle mass index,SMI)、肌少症指数(Sarcope-nia index,SI)与呼吸危重症患者营养状态及预后的关系。方法选取2021年9月至2023年8月南通市第一人民医院收治的呼吸危重患者132例。采用改良危重症营养风险评分表(The modi-fied nutrition risk in critically ill,mNUTRIC)评估患者营养状况,根据评分结果分为低风险患者(n=83)、高风险患者(n=49),比较低风险患者与高风险患者的SMI、SI。以离开ICU为时间终点评估预后,分为死亡组(n=37)和存活组(n=95),比较死亡组与存活组患者的一般资料,采用多因素Logistic回归模型分析影响呼吸危重症患者死亡的因素,受试者工作特征(Receiver operator characteristic,ROC)曲线分析SMI、SI预测呼吸危重症患者死亡的风险价值。结果与低风险患者相比,高风险患者的SMI、SI降低(P<0.05)。以离开重症监护室(Intensive care unit,ICU)为评估时间终点,与存活组相比,死亡组年龄、入院24 h内的急性生理评分、年龄评分及慢性健康评分(Acute physiology and chronic health evaluation scoring system,APACHEⅡ)评分及降钙素原(Procalcitonin,PCT)水平较高,白蛋白(Albumin,ALB)、SI和SMI则较低(P<0.05)。多因素Logistic回归模型显示,高APACHEⅡ评分及低SMI、SI值是影响呼吸危重症死亡的独立危险因素。ROC曲线显示,SMI、SI单独预测呼吸危重症患者死亡的曲线下面积(Area under curve,AUC)为0.784(0.720~0.839)、0.726(0.657~0.788),采用SMI、SI联合预测AUC为0.890(0.835~0.938),联合预测效能较单独预测效能更好(P<0.05)。结论SMI、SI与呼吸危重症患者营养状态关系密切,两者联合预测呼吸危重症患者死亡的临床价值高于单独预测。
文摘Two common problems for a typical Power distribution system are voltage collapse & instability. Challenge is to identify the vulnerable nodes and apply the effective corrective actions. This paper presents a probabilistic fuzzy approach to assess the node status and proposes feeder reconfiguration as a method to address the same. Feeder reconfiguration is altering the topological structures of distribution feeders by changing the open/closed states of the sectionalizing and ties switches. The solution is converge using a probabilistic fuzzy modeled solution, which defines the nodal vulnerability index (VI) as a function of node voltage and node voltage stability index and predicts nodes critical to voltage collapse. The information is further used to plan best combination of feeders from each loop in distribution system to be switched out such that the resulting configuration gives the optimal performance i.e. best voltage profile and minimal kW losses. The proposed method is tested on established radial distribution system and results are presented.
